Large networks, such as the Internet, which may provide the infrastructure for many peer-to-peer systems, are now being used to provide a variety of services to users. For example, media services, such as streaming and transcoding, web-services for e-commerce, such as airline and hotel reservations, or grid computing services for computation and data may be available via large networks.
A fundamental challenge in effectively utilizing these network services is to efficiently and quickly locate desired services in large networks, such as the Internet. The challenge of discovering services is complicated by several factors. For example, if a centralized information service for facilitating such discovery were used, such as a centralized information service used for peer-to-peer file sharing systems, it would not easily scale as the number of available services and number of users increases. In addition, each service has several dynamic attributes, e.g., load and latency, that keep changing and need to be updated in the information service. The desired update rate may not be sustained by a centralized information service. Also, providing an information service with minimal downtime may require several system administrators to maintain and would be costly. Finally, the information service should be locality-aware for faster response times. For example, a query including a request for a desired service should be directed to a node in the network proximity of the node initially sending the query, and the services returned as a response to the query should also be in the network proximity of the querying node.